This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This project focuses on the mechanism of action of Laromustine, a sulfonylhydrazine anticancer prodrug currently in clinical trials for acute myelogenous leukemia and glioma multiforme. The activity of Laromustine is a function of two reactive electrophiles that are generated upon base-catalyzed activation in situ: a 2-chloroethylating species and methylisocyanate. The 2-chloroethylating species ultimately forms cytotoxic, interstrand DNA crosslinks, and the carbamoylating activity of methylisocyanate synergizes with the 2-chloroethylating activity, resulting in significant cytotoxicity to neoplastic cells. These in situ chemical processes are similar to those of other anticancer compounds, including nitrosoureas. This project will involve an investigation of several enzymes as targets likely to be modified with a carbamoyl group from methylisocyanate so as to explain the synergistic cytotoxicity. In addition, the effects of exposure to studied agents on gene expression, signaling pathways, and cell death mechanisms will be elucidated. The proposed research will greatly enhance the understanding of the relationship between the chemical reactivity of these compounds and their observed pre-clinical and clinical effects, which potentially could lead to more effective chemotherapeutic strategies.